The fire protection requirements of fire protecting elements are classified in fire resistance categories, according to DIN 4102, Part 5. The fire resistance capacity of a fire protecting gate is determined based on the duration, at which at a certain temperature increase on one side of the fire protection hate, the other “cold” side of the fire. The fire protection requirements of fire protecting elements are classified in fire resistance categories, according to DIN 4102, Part 5. The fire resistance capacity of a fire protecting gate is determined based on the duration, at which at a certain temperature increase on one side of the fire protection gate, the other “cold” side of the fire protection gate remains under a defined threshold temperature. These fire resistance categories are also valid for fire protection gates. The duration in minutes until the threshold temperature is being attained on the cold side, is designated the resistance time. This determines the classification in the different fire resistance categories. A classification of a fire protection gate in fire resistance category T30 implies in a minimum resistance time respective of T60 and T90, a 60 minutes and 90 minutes resistance time. During these resistance times, it must be insured that the room-closing effect of the fire protection gate is guaranteed, i.e. during these times, no flame may exit the gate on the side opposite to the fire, resulting from combustion of the firing load, i.e. organic binding agent.
As a consequence of the fire protection requirements relative to fire protection doors, as mineral wool insulating material for inserts of fire protection doors, predominantly rock wool is being used, in view of its high temperature resistance, who melting point according to DIN 4102, Part 17, should be around 1.000° C. Usually this type of rock wool is being produced pursuant to the so called nozzle blowing process or with external centrifugation, for example the so called cascade centrifugation process. The fibers thus produced normally present, according to their usage, an average geometric diameter above 4 to 12 μm, so that these fibers—compared to fiber of traditional glass wool—are relatively coarse. Glass wool fibers, on the other hand, according to these, feature an average geometric diameter in the range of 3 μm until 6 μm. In the case of rock wool, however, as a result of the production pursuant to the nozzle blowing process or with external centrifugation, forcibly a large portion of non fibrillated material in form of coarser fiber components results in the form of so-called “beads” with a particle size of at least 50 μm in the insulating material and commonly with a portion from 10 to 30% of the fiber portion of the insulating element. This comparably high bead portion participates of the weight of said insulating element, but does not contribute in any way to the desired insulating effect of the insulating element.
As binding element, for rock wool fibers, normally a phenol-formaldehyde resin is being utilized, which is being integrated into the fire protection gate as organic material, the so-called fire load. The content of binding agent which is required for the structural stabilization of the soft rock wool fleece for the formation of a solid plate of agglutinated rock wool, at fire protecting units is normally below 1 weight % (dry, referred to the fiber mass). Based on the coarse fiber structure of conventional rock wool, as compared to conventional glass wool, to form fire protection insets, high gross densities are needed, in order that the desired insulating effect may be attained. The gross density of such rock wool insets, according to the fire resistance category, is for example 120 kg/m3 until 230 kg/m3.
Such high gross densities, required to attain the desired insulating effect, at a given thickness of fire protection units for fire protection gates directly result in too heavy gate weights. In addition, a large density also forcibly implies that—considered on an absolute basis—a relatively large amount of binding agent and, consequently, fire load, is being introduced in the fire protection gate.
Since the thermal insulating effect of said rock wool inset, with predetermined thickness, separately is frequently insufficient to attain a required fire resistance category, it is often necessary to provide additional fire protection means, which, in the event of a fire, in consequence of the correlate temperature increase, liberate physically and/or chemically bound water, thus rendering slower the temperature increase. Such fire protection means may be applied in different layers, as is known from EP 0 741 003, or are integrated in the rock wool material specifically, as known from EP 1 097 807.
The high gross densities of the conventional rock wool materials, used for the fire protection insets, result not only to correspondingly high weights of the insets and, therefore, also of the fire protection gates, but additionally they imply in that as a result of their surface extent, during the manipulation, eventually during the introduction into the fire protection gate, the insets are exposed to high flexing loads due to their specific weight, featuring a trend to delaminate when being raised or even forming fissures. Therefore, an extremely careful manipulation of these fire protection insets is required, which has unfavorable results vis-à-vis a rational production. This mechanical instability of the inset evidences, as a consequence, that the procedure of introducing the inset into the gate box at many fire protection gate manufacturers is the only procedure, which so far could not be automatized.
Products with high gross density are being produced by a corresponding thickening of the fleece which forms the respective products. Said fleece, before and during their passage through the hardening oven, are being compressed by the compression forces acting upon them, in order to adjust a predetermined form, and after elimination of said compression forces, the hardened binding means accepts the profiling task. Inside the material of the rock wool, quite intensive resetting forces are active, which have to be offset through the effect of the binding agent. The stronger the material has been compressed, the more intensive are these forces, i.e. according to the extent of the gross density.
During the aging process of said rock wool material after integration of the fire protection gate, however, binding forces of the biding agent may be neutralized with the passage of time. As a result, the resetting forces, “frozen” as it were, are being liberated and the rock wool inset may bulge. The forces then incident may become so intense that their considerably deform the steel plate shells of the fire protection gate, so that the gate needs to be replaced.
In order to be able to dominate said resetting forces at a somewhat better level, in normal usage procedures were undertaken according to which in front of said hardening oven, a pressure cylinder exposes to local pressure said not hardened rock wool material, when fibers are being broken, i.e. are being filled. As a result, the resetting forces are somewhat reduced, but the consequence is that the fiber connection may be considerably damaged. Also the resistance of the inset will thus be affect; which may evidence unfavorable effects during their manipulation.
The rupture of fibers caused by the compression cylinder is liable to result, additionally, in a considerable formation of dust, so that dust and fiber particles, as well as beads, during the insertion of the fire protection inset into the gate box may generate impurities at said box. These impurities may result in erroneous adjustment during welded connection at the subsequent welding procedures to close the gate box with the gate cover, so that complex quality controls and eventual subsequent labor will be required.